Root and Stem Rot of Cucumber Caused byFusarium oxysporumf. sp.radicis-cucumerinumf. sp. nov.

Root and stem rot of cucumber (Cucumis sativus) caused by a new Fusarium oxysporum forma specialis is reported for the first time. Of 18 cultivated species from six different botanical families that were artificially inoculated, two species of Cucurbitaceae-mdon (C. melo) and sponge gourd (Luffa aegyptiaca)-showed root and stem rot similar to that caused by isolates of F. oxysporum that attack cucumber. Optimum temperature for disease development was close to 17°C. Disease symptoms and pathogenicity tests confirm that a new forma specialis of F. oxysporum is the incitant of the disease. The author proposes to name this forma specialis as F. oxysporum f. sp. radicis-cucumerinum f. sp. nov.